The art is replete with sheet materials that can be cut into smaller pieces to form portions of fasteners, and methods for making such sheet materials. U.S. Pat. Nos. 2,933,797; 3,009,235; 3,136,026; 3,154,837; 3,577,607; 3,673,301; 3,943,981; and 4,024,003 provide illustrative examples. Generally these patents describe sheet materials including backings formed by intersecting backing yarns (e.g., intersected by weaving or knitting) from one surface of which backings project portions of pile yarns that form either loops, hooks formed by cutting loops along one side, or projections that have enlarged heads at their distal ends which may be engaged with other such projecting portions on other pieces of such sheet materials to form fasteners.
With fasteners of the type described above, it is important to anchor portions of the pile yards entwined in the backing so that the fastener will function properly. Various anchoring means have been described or known in the prior art to provide such anchoring, including tight weaving of the base and pile yarns, coating or impregnating the backing with an adhesive-like binding material, or including a thermoplastic yarn in the backing that is subsequently heated to cause the yarn to both adhere to adjacent yarns to anchor them while retaining sufficient structural strength to maintain the integrity of the backing. Such prior art anchoring means have typically significantly increased the cost of the resulting sheet materials because of the added materials or added processing steps they require, or in the case of the thermoplastic yarn, required tight packing of the yarn in the backing and a difficult processing step to produce the uniform processing temperature required.